This invention relates broadly to the control and operation of dual gas compressors and more particularly to dual gas compressing apparatus wherein the gas compressors can be selectively operated in either a dual parallel mode for producing gas at a single pressure level or in a series mode for producing gas at two separate pressure levels.
In U.S. Pat. No. 2,576,876 issued on Nov. 27, 1951, to inventor H. R. Gamble, there is taught a dual stage compressor which can be operated either as a parallel single low pressure compressor or as a series single high pressure compressor. The changes required to convert from one operation to the other is time consuming and requires a bleed down of air pressures and mechanical changes to the device. This teaching does not include a simultaneous production and storage of two separate pressure levels of compressed gas nor does it teach when in the series configuration reducing the heat of compression by conducting the hot compressed gas from the first compression stage to a remote location for cooling of the gas and as an aid to maintain a cool compressor.
The U.S. Pat. No. 2,765,976 issued Oct. 9, 1956 to inventor W. A. Steward teaches only a series two stage compressor with one level of compressed gas pressure.
U.S. Pat. No. 3,031,131 issued Apr. 24, 1962, to inventor E. J. Hilderbrandt, like the last referenced patents, teaches a two stage series compressor with only one level of available compressed gas pressure.
U.S. Pat. No. 3,476,485 issued Nov. 4, 1969, to inventor F. K. Kimderman, teaches a series three stage compressor with only one level of available compressed gas.
U.S. Pat. No. 3,001,692 and 3,574,474 are directed to multi-stage gas compression and methods of control respectively.
There has not been a low cost gas compressing system which is selectable to produce a large volume of compressed gas at low pressure or a smaller volume of low pressure gas and high pressure gas simultaneously until the emergence of the instant invention.